The linear temperature dependence of the paramagnetic resonance linewidth in the manganate perovskites and

Seehra, M. S.; Ibrahim, Manjula M.; Babu, V. Suresh; Srinivasan, G.

doi:10.1088/0953-8984/8/50/048

Cited by 52 publications

(35 citation statements)

References 22 publications

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“…The observation is in agreement with a reduction in both the ferromagnetic Curie temperature and magnetization for LSMO-PZT, as discussed in the previous section. The gvalues for the layered samples are in agreement with values for bulk manganites [17].…”

Section: Ferromagnetic Resonancesupporting

confidence: 81%

Structural and magnetoelectric properties of MFe 2 O 4 ?PZT (M?=?Ni,Co) and La x (Ca,Sr) 1-x MnO 3 ?PZT multilayer composites

Srinivasan

Rasmussen

Bush³

et al. 2004

Applied Physics A: Materials Science & Processing

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Thick film layered magnetoelectric composites consisting of ferromagnetic and ferroelectric phases have been synthesized with nickel ferrite (NFO), cobalt ferrite (CFO), La 0.7 Sr 0.3 MnO 3 (LSMO), or La 0.7 Ca 0.3 MnO 3 (LCMO) and lead zirconate titanate (PZT). Structural, magnetic and ferromagnetic resonance characterization shows evidence for defect free ferrites, but deterioration of manganite parameters. The resistivity and dielectric constants are smaller than expected values. The magnetoelectric effect (ME) is stronger in ferrite-PZT than in manganite-PZT. The ME voltage coefficient α E at room temperature is the highest in NFO-PZT and the smallest for LCMO-PZT. The transverse ME effect is an order of magnitude stronger than the longitudinal effect. Multilayer composites consisting of alternative layers of magnetostrictive and piezoelectric materials are observed to show a strong magnetoelectric (ME) effect and are of interest for studies on ME interactions and for potential use in devices [1][2][3][4][5]. Such structures when placed in an external ac magnetic field δH undergo deformation of the magnetic layer due to magnetostriction, resulting in an electrical polarization of the dielectric layer due to piezoelectric effect [6,7]. The ac electrical field δE produced in the structure is a "productproperty" and is proportional to the piezomagnetic and piezoelectric coefficients of the constituent phases [8]. The magnetoelectric voltage coefficient α E = δE/δH for such composites is in the range 50-5000 mV/Oe cm, depending on the nature and volume of the magnetic and piezoelectric phases [1][2][3][4]6,7]. These values far exceed the ME coefficient of 20 mV/Oe cm for Cr 2 O 3, the best single phase ME material [9].Theoretical models for a bilayer with parameters of nickel or cobalt ferrite and lead zirconate titanate predict coefficients as high as 1.5 V/Oe cm [7]. Although our studies reveal strong ME interactions in nickel ferrite -PZT samples, systems such as cobalt ferrite-PZT show a weak coupling [10]. The reason could be deterioration of physical properties of individual layers and poor mechanical coupling between the two phases due to defects at the interface formed during the sample processing [3,4,6]. A detailed and comprehensive investigation of structural, electrical and magnetic properties of the structures is important to elucidate the cause of magnetoelectric coefficient limitations.This report details the fabrication and characterization of multilayer thick film structures consisting of piezoelectric (lead zirconate titanate) and ferromagnetic (nickel ferrite, cobalt ferrite, and lanthanum-strontium or calcium manganite) phases. The choice of materials for the structures is due to the following reasons. All the materials, except the manganites, have ferromagnetic or ferroelectric phase transition temperatures well above the room temperature. Piezoelectric lead zirconate titanate (PZT) has high dielectric permeability and high piezoelectric coupling constants. Both nickel and cobalt fer...

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Section: Ferromagnetic Resonancesupporting

confidence: 81%

Structural and magnetoelectric properties of MFe 2 O 4 ?PZT (M?=?Ni,Co) and La x (Ca,Sr) 1-x MnO 3 ?PZT multilayer composites

Srinivasan

Rasmussen

Bush³

et al. 2004

Applied Physics A: Materials Science & Processing

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“…In manganites undergoing a transition from a paramagnetic to ferromagnetic state, the linewidth ∆H(T) in the paramagnetic state is found to increase quasilinearly with increasing T. Different models have been proposed to explain this result such as contribution from spin-phonon interaction 11 , a relaxation bottleneck behavior 20,21 or in terms of a combined effect of DM and CF interactions 12 . The latter model seems to be able to explain most of the CMR EPR linewidth results and can be described in terms of the equation, ∆H(T) = [χ 0 (T) / χ(T)] ∆H(∞) where χ 0 (T) ∝ T -1 is the free ion (Curie) susceptibility, χ(T) is the measured susceptibility and ∆H(∞) is a temperature independent constant attributable to the high temperature limit of the linewidth.…”

Section: Resultsmentioning

confidence: 99%

Anomalous spin dynamics in the charge-ordered two-electron doped manganiteCa0.9Ce0.1MnO3: Possibility of a spin-liquid phase

2006

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The 'two-electron' doped rare earth manganites Ca 1-x Ce x MnO 3 (x = 0.1, 0.2) are probed using resistivity, ac susceptibility and electron paramagnetic resonance (EPR) measurements across their respective charge ordering (CO) temperatures T CO = 180 K and 250 K. The EPR 'g' factor and intensity as well as the transport and magnetic behaviors of the two compositions are qualitatively similar and are as expected for CO systems.However, the EPR linewidth, reflective of the spin dynamics, for x = 0.1, shows a strongly anomalous temperature dependence, decreasing with decreasing temperature below T CO in contrast with the sample with x = 0.2 and other CO systems. Keeping in view the evidence for magnetic frustration in the system, we propose that the anomalous temperature dependence of the linewidth is the signature of the occurrence of a disorder driven spin liquid phase, present along with charge ordering.

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“…Moreover, since the relative strength of q  0 modes is decreased with lowering temperature, it follows that the anisotropy will also decrease. Indeed, such behavior was experimentally observed for the plenty of 2D antiferromagnets [57][58][59][60][61][62][63][64][65] and linear dependence of the B was usually associated either with phonon modulation of the anisotropic and antisymmetric exchange interactions with the magnitude of the dependence proportional to intralayer exchange parameter J 4 or with the crystalline field, the latter for S > ½ case. For transition metals where the orbital contribution to the ground state is severely quenched, the latter interactions are rather small and give rise to d(B)/dT usually smaller or equal 0.1 mT/K.…”

Section: B Electron Spin Resonancementioning

confidence: 90%

Zigzag antiferromagnetic quantum ground state in monoclinic honeycomb lattice antimonatesA3Ni2SbO6(A=<

et al. 2015

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We present a comprehensive experimental and theoretical study of the electronic and magnetic properties of two quasi-two-dimensional (2D) honeycomb-lattice monoclinic compounds A 3 Ni 2 SbO 6 (A=Li, Na). Magnetic susceptibility and specific heat data are consistent with the onset of antiferromagnetic (AFM) long range order at low temperatures with Néel temperatures ~ 14 and 16 K for Li 3 Ni 2 SbO 6 and Na 3 Ni 2 SbO 6 , respectively. The effective magnetic moments of 4.3  B /f.u. (Li 3 Ni 2 SbO 6 ) and 4.4  B /f.u. (Na 3 Ni 2 SbO 6 ) indicate that Ni 2+ is in a high-spin configuration (S=1). The temperature dependence of the inverse magnetic susceptibility follows the Curie-Weiss law in the high-temperature region and shows positive values of the Weiss temperature ~ 8 K (Li 3 Ni 2 SbO 6 ) and ~12 K (Na 3 Ni 2 SbO 6 ) pointing to the presence of nonnegligible ferromagnetic interactions, although the system orders AFM at low temperatures. In addition, the magnetization curves reveal a field-induced (spin-flop type) transition below T N that can be related to the magnetocrystalline anisotropy in these systems. These observations are in agreement with density functional theory calculations, which show that both antiferromagnetic and ferromagnetic intralayer spin exchange couplings between Ni 2+ ions are present in the honeycomb planes supporting a zigzag antiferromagnetic ground state. Based on our experimental measurements and theoretical calculations we propose magnetic phase diagrams for the two compounds. 75.30.Kz; 75.10.Dg; 75.30.Gw; 75.30.Et

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The linear temperature dependence of the paramagnetic resonance linewidth in the manganate perovskites and

Cited by 52 publications

References 22 publications

Structural and magnetoelectric properties of MFe 2 O 4 ?PZT (M?=?Ni,Co) and La x (Ca,Sr) 1-x MnO 3 ?PZT multilayer composites

Structural and magnetoelectric properties of MFe 2 O 4 ?PZT (M?=?Ni,Co) and La x (Ca,Sr) 1-x MnO 3 ?PZT multilayer composites

Anomalous spin dynamics in the charge-ordered two-electron doped manganiteCa0.9Ce0.1MnO3: Possibility of a spin-liquid phase

Zigzag antiferromagnetic quantum ground state in monoclinic honeycomb lattice antimonatesA3Ni2SbO6(A=<

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